1. Field of the Invention
The present invention relates to a power and signal extender and a circuit board, and more particularly, to a power and signal extender and a circuit board capable of maintaining the ground plane integrity of the circuit board.
2. Description of the Prior Art
The printed circuit board (PCB), which is the most widely utilized circuit device at the present time, is utilized as a supporter of various electronic elements and provides circuit connections between different electronic elements. During the production process of PCB, a predefined circuit may be realized on the PCB via specific production steps such as development and etching. The active elements and/or passive elements on the PCB maybe incorporated with different circuit structures to realize the functions required by various electronic products.
Most of common PCBs have multiple-layer structures, and there are via holes deployed on the PCBs, so that circuits may transmit between different layers through the via holes. An ideal PCB has advantages such as well heat dissipation, high signal stability, low electromagnetic interference (EMI) and excellent electrostatic discharge (ESD) protection capability. However, due to the requirements of cost reduction, modern electronic products are always implemented with PCB having fewer layers (e.g., a double layer board) , resulting in losses of signal stability, heat dissipation capability, EMI performance, ESD protection capability of the PCB. For example, the common signal deployment for a double layer board structure is that power and various signals are deployed on the upper layer, and that the system ground is deployed on the lower layer. When there are two different signal wires crossing over each other, one of the signal wires may change to pass through the lower layer from a via hole. Therefore, an area on the lower layer should be segmented from the ground plane for the deployment of signal wire, resulting in imperfection of the ground plane. If there are more numbers of signals having to pass through the lower layer, more areas should be segmented from the ground plane located on the lower layer, for transmissions of the signals. The ground plane will therefore become fragmentary. The fragmentation of ground plane will give rise to more problems, such as discontinuous impedance, worse heat dissipation capability, more severe EMI problem and worse ESD protection capability.
For example, please refer to FIG. 1, which is a schematic diagram of circuit structure of a double layer board 10. As shown in FIG. 1, the double layer board 10 includes a package 100, circuit devices 102, 104 and a power supply module 106. An integrated circuit (IC) 108, which is included in the package 100, is utilized for performing specific functions. Signals between the IC 108 and other devices or modules on the double layer board 10 may be transmitted via transmission wires W1-W3. The power supply module 106 supplies a first power P1 for usage of the IC 108 and the circuit devices 102, 104. The IC 108 further obtains a second power P2 from the power supply module 106, for performing several specific applications.
In the double layer board 10, most power and signal wires are deployed on the upper layer and the ground plane is deployed on the lower layer. The ground plane should possess its integrity, which allows the double layer board 10 to have enough stability and heat dissipation capability, and further have enough capability against the EMI and ESD. In several conditions, however, the power or signal wires located on the upper layer should still pass through the lower layer. For example, as shown in FIG. 1, the transmission path of the first power P1 to the circuit device 102 is interrupted by the transmission wire W1; hence, the first power P1 may pass through the via hole to the lower layer and change to be transmitted on the lower layer (or the transmission wire W1 may be transmitted to the lower layer). The transmission path of the first power P1 to the circuit device 104 is also interrupted by the second power P2, where the first power P1 also pass through the via hole to the lower layer and change to be transmitted on the lower layer (or the second power P2 may be transmitted to the lower layer). However, the transmission of the first power P1 on the lower layer of the double layer board 10 must segment the area of ground plane located on the lower layer, which causes imperfection of the ground plane and thereby generates the problems such as discontinuous impedance, worse heat dissipation capability, more severe EMI problem and worse ESD protection capability as mentioned above.
In order to solve the above problem, more costs are always required. For example, a PCB designer may apply a large heat sink to solve the heat dissipation problem, or add an ESD protection device on the PCB to enhance the ESD protection capability. In such a situation, the low cost benefits of the PCB having fewer layers will disappear. Thus, there is a need for improvement over the prior art.